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Thread: Static thrust

  1. #1
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    Default Static thrust

    What are some of the ways people use for measuring static thrust ? I was going to tie a rope to the rear of the craft with some hanging scales mounted in line and then tie the other end to a wall/post/towbar etc but i'm finding it differecult to locate some appropriate scales , let alone some that will go up to 200 - 400 pounds. So what are some alternative ways please.



    And the process i briefly explained above what is the "correct" name for those types of scales ? i call them spring or hanging scales but thats obviously not right cause i cant find them under that name hehe.

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    Default Re: Static thrust

    Hi Lazza,



    The scales you were thinking of using are called a spring balance. If you pop that into google then you should be able to find something.



    I have used that method to measure my thrust before, it does get a bit windy for the person doing the reading! I think the balance I used was used to weigh meat but i'm not sure.....



    Nick

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    Default Re: Static thrust

    What I did that worked was, take a piece of wide marsking tape and stick it over the slide area where the guage runs, then do your test and OH by the way, take up the slack first, when when you feel the first resistance then only give it plenty.



    I found that this works realy well and you can do it over and over, just replace the marsking tape each time.



    So, the wife can keep her hear doooo.



    Hope this helps, if it sounds Idiotic, Ignor it.

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    Default Re: Static thrust

    i use the spring balance method but another is to position a set of bathroom scales on a wall and push against it -



    don't pay too much attention to the actual reading but use it as a comparison i.e. higher or lower than the last time



    a quick approximate conversion is 100 Newtons for every 10Kg on the scales



    100 Newtons = 22 lbs thrust(approx) if you want to convert



    hope that helps



    Tony

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    Default Re: Static thrust

    One other I would like to add is to make sure that there isn't a wall or other vertical surface close behind the craft. I found that the thrust air hitting a wall showed a higher reading and also generated turbulance. The best thing I found to tie to was a rugby post in the middle of a big pitch!


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    Default Re: Static thrust

    Why not use some fairly low range newton meters available from a hardware, school suppliers and hook it up to a block and tackl in reverse so a small movement produces a big movement of the end connected to the spring balance, the force is alot less. This means an acurate reading would be taken using cheap available balances. Just a thought. The more bloacks and tackles you use the less force will be put on the the spring balance but the further it will pull. Also remember that the more you use the more friction so it will be less accurate.



    [img]index.php?t=getfile&id=146&private=0[/img]



    Nick
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    Default Re: Static thrust

    Thanks , i may end up going with a idea like that yet because i'm un able to find a siutable spring balance so far and my bathroom scales are digital ones that turn off if not pushed within 10 seconds, so either way i will have to find something. I'll keep looking




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    Default Re: Static thrust

    In theory pulleys and ropes could be used to put the spring balance where the driver can see it, or at least out of the air blast. But when I tried it the friction in the pulleys was too great. It might work with very high spec ball bearing ones, but its probably just another source of error you can do without.



    I use the ropes set up in a Y to back of the craft to keep it from turning. What you then have to do is to use the rudder(s) to keep the whole assembly in the right direction. You will find though that the steering works backwards.



    Nick


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